e46 Coolant Leak

[theholyblade]

I was driving to work a few days ago and a truck in front of me dropped a big metal scoop shovel. Due to traffic and speed I was not able to swerve out of the way and drove right over it. Now my engine can't hold coolant too well. I'm thinking it may have cracked the coolant drain plug, but I haven't had the chance to really get in the engine to look around.
Am I far off in thinking there is something wrong with the drain plug, or the expansion tank?

[Manolito]

Assuming that you have an automatic transmission, there are a number of plastic water-containing components at the bottom of the expansion tank that could have gotten hit. With a manual, there is a lot less stuff, but what is there is plastic and it is the lowest spot that has coolant in it. If it has not been replaced yet, all that old brittle plastic stuff is due for replacement anyway so you didn't really loose anything.